Size : 2 Litre

• Coarse, high-purity calcium reactor media
• Provides calcium, magnesium, strontium, potassium, and carbonates
• 1-3 cm grain size

Reef Reactor™ is a high-purity source of aragonite, which supplies all important elements for optimal ionic balance and robust coral growth and coloration in reef aquaria. It has a grain size of approximately 1-3 cm. It is intended for use in calcium reactors where it is dissolved slowly with the addition of CO₂. As it dissolves, it provides calcium, magnesium, strontium, potassium, and carbonates among other important elements for reef aquaria. It is excellent at increasing and stabilizing alkalinity, which also supports a stable pH and encourages the rapid formation of coral skeletal material. With high levels of both calcium and magnesium, it offers an excellent means of balanced supplementation for rapid growth and propagation of corals and calcareous animals in reef aquaria. It possesses the highest level of soluble potassium of all competing brands while exhibiting the lowest levels of both aluminum and phosphorus.

Compatibility

Grain size 1–3 cm. Seachem item #1541 (2 L). The coarse grade — Reef Reactor Md is the 0.5–1 cm version of the same aragonite.

Coarse grain means slower dissolution and less packing. A large chamber with strong recirculation suits this grade; it resists compacting and channelling better than a fine media does over months of running.

For calcium reactors, and nothing else. This is not a substrate and not a filter medium to sit in a bag. It is meant to be dissolved slowly by CO₂-acidified water inside a reactor chamber.

As it dissolves it supplies calcium, magnesium, strontium, potassium and carbonates, among other elements. It is very good at raising and stabilising alkalinity, which in turn holds pH steady and speeds up skeletal growth.

Seachem’s comparative claim: the highest soluble potassium of all competing brands, with the lowest levels of both aluminium and phosphorus. Phosphorus is the one that matters in practice — a reactor media that leaches phosphate feeds your tank algae continuously.

Follow your reactor manufacturer’s instructions for flow and CO₂. The rate at which this media dissolves is set by the flow through the chamber and the pH inside it, and both of those are your reactor’s settings, not a property of the media.

Seachem name the two test kits they expect you to be reading while you set the reactor up: Reef Status: Calcium and Reef Status: Magnesium. Effluent chemistry is the only thing that tells you whether the flow rate and CO₂ rate you have chosen are right.

Safety & Precautions

Seachem publish no hazard statement for this media. It is aragonite gravel. There is no warning on their page for us to reproduce, and we are not going to write one that sounds official.

Rinse it before it goes in. Aragonite carries dust, and dust in a calcium reactor ends up as cloudiness in the display.

The hazards in this setup belong to the reactor, not the media. Pressurised CO₂, regulator handling and the risk of a runaway pH drop in the display if the reactor floods are all covered by your reactor’s own manual. Read that one before you commission it.

Commission a reactor slowly and watch the display. The effluent from a calcium reactor is acidic by design. Getting the CO₂ and flow rates wrong at the start moves tank pH further and faster than any dosing product would.

What’s in the Box

2 litres of coarse aragonite reactor media, grain size 1–3 cm. Seachem item #1541.

Media only. No reactor, no CO₂ equipment, no test kits. Seachem also make this in a 4 L pack, item #1542.

Seachem publish no parts or accessory list for this pack, and their own product photography shows the container alone. We would rather tell you that than invent a contents list. If you need to know whether a particular pack ships with a scoop before you order, ask us and we will open one and look.

Warranty & Support

This product is covered by warranty as per the manufacturer policy, against material and manufacturing defects from the date of purchase.

Warranty support is handled by us directly. Message our WhatsApp support with your order number and we will diagnose the fault first. Most cases are solved by replacing a single part, so you rarely need to send the whole unit. If the item does need to come back, it ships to our Delhi or Pune warehouse, whichever one served your order, and courier cost in both directions is borne by the customer. Your GST invoice is valid proof of purchase for the claim.

Returns & Replacement

Returns are accepted within 7 days of delivery, provided the item is unused and in its original packaging. Manufacturer-sealed items cannot be returned once the seal is broken, and sale-priced items are not refundable.

If your item arrives defective or damaged, message us on WhatsApp with your order number, or email us if you would rather, and we will replace it. Approved replacements are delivered within 3 to 5 business days. Transit damage is covered by insurance on every shipment. If tracking shows delivered but nothing reached you, tell us within 72 hours, which is the reporting window Indian couriers allow. Damage caused during installation or use is not covered; replacement spares for such cases are chargeable.

Full terms are on our Cancellation & Returns page.